docs: def clone(cls, variable, **kwargs):
          """
          Make a copy of another variable. The variable being copied can be of the same type or belong to
          a different solver interface.
  
          Example
          ----------
          >>> var_copy = Variable.clone(old_var)
          """
          return cls(variable.name, lb=variable.lb, ub=variable.ub, type=variable.type, **kwargs)